First Look by the Yutu-2 Rover at the Deep Subsurface Structure at The

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https://doi.org/10.1038/s41467-020-17262-w OPEN First look by the Yutu-2 rover at the deep subsurface structure at the lunar farside ✉ Jialong Lai 1,2,YiXu 1 , Roberto Bugiolacchi 1,3, Xu Meng1,4, Long Xiao1,5, Minggang Xie 1,6, Bin Liu7, Kaichang Di7, Xiaoping Zhang1, Bin Zhou 8,9, Shaoxiang Shen8,9 & Luyuan Xu 1

The unequal distribution of volcanic products between the Earth-facing lunar side and the farside is the result of a complex thermal history. To help unravel the dichotomy, for the ﬁrst

1234567890():,; time a lunar landing mission (Chang’e-4, CE-4) has targeted the Moon’s farside landing on the floor of Von Kármán crater (VK) inside the South Pole-Aitken (SPA). We present the first deep subsurface stratigraphic structure based on data collected by the ground-penetrating radar (GPR) onboard the Yutu-2 rover during the initial nine months exploration phase. The radargram reveals several strata interfaces beneath the surveying path: buried ejecta is overlaid by at least four layers of distinct lava flows that probably occurred during the Imbrium Epoch, with thicknesses ranging from 12 m up to about 100 m, providing direct evidence of multiple lava-infilling events that occurred within the VK crater. The average loss tangent of mare basalts is estimated at 0.0040-0.0061.

1 State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China. 2 School of Science, Jiangxi University of Science and Technology, Ganzhou, China. 3 University College London, Earth Sciences, London, UK. 4 School of Civil Engineering, Guangzhou University, Guangzhou, China. 5 Planetary Science Institute, School of Earth Sciences, China University of Geosciences, Wuhan, China. 6 College of Science, Guilin University of Technology, Guilin, China. 7 State Key Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Science, Beijing, China. 8 Key Laboratory of Electromagnetic Radiation and Detection Techonology, Chinese Academy of Sceience, Beijing, China. 9 Aerospace ✉ Information Research Institute, Chinese Academy of Science, Beijing, China. email: [email protected]

NATURE COMMUNICATIONS | (2020) 11:3426 | https://doi.org/10.1038/s41467-020-17262-w | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-020-17262-w

nraveling the shallow subsurface structure of the lunar lasted about 200–600 Ma21,31, with the youngest flows estimated Umare offers the key to a better understanding of the local between 3.15 and 3.6 Ga19,21. However, currently, no direct evi- history of basaltic volcanism, an important process cou- dence of the volcanic history of VK crater indicates whether the pled to the Moon’s thermal evolution1. The thickness and surface mare deposits were formed by one episode of basaltic volcanism area of basalt layers can be used to constrain lava eruption based on the uniform reflectance spectral characteristics or volumes. A range of remote-sensing data including the study of multiple lava-infilling events19. LPR can provide first-hand data impact craters morphology2,3, the analysis of high-resolution to disclose the subsurface stratigraphy and constraint the thermal gravity data4, and the reflectance spectra of crater ejecta depos- history. its5–8 have contributed to developing the current model of lunar VK’s neighboring region is geologically highly complex: the evolution. map I-104731 and the inset32 (Supplementary Fig. 1) show a Ground-penetrating radars on the lunar surface and radar superposition of impact morphologies spanning from the pre- sounders onboard orbiting spacecraft have helped to investigate Nectarian to the Copernican epochs. The neighboring impacts the physical properties of the sub